[...] actual AFR goes very lean when I get completely off the throttle and just coast down.. Like CIS has a natural fuel cut overrun or something.. See the yellow spike right after the pull on top (AFR) with the yellow drop on bottom (TPS)..

Well I admire you for tuning CIS with Megasquirt
Any kind of spike like that should not happen. It goes lean, while normally it should go rich after closing TB. Maybe it's because when you let the pedal off, the TB closes, excess of boost goes via WG BEFORE your O2 sensor or JUST AFTER and creates back pressure in exhaust and it looks like this spike?

kondzi I think you might be on the right track..
My BOV is up by my TB but blows the excess back into the intake between the turbo and AFM.
So my boost blowoff could definitely be pushing my airplate up when I drop the throttle..

Maybe I will try it some time with the BOV just dumping to atmosphere like normal cars and see if it spits flames instead..

MAP just goes straight to high vacuum though, where lean is fine and it might just be covered up by overrun fuel cut anyway..

I think if I drill out the CSV hole bigger, to give the IAT sensor more space between the element and the manifold metal, it could help it read better..
So maybe I'll drill it out half way big enough to tap for the sensor and keep my adapter flange in play, see how that does.._________________80 Turbo - Slightly Modified

Took out some more fuel..
I've got it beat down in this area pretty good..
In the 3D map you can see where I have it "trampled down" from the base map I started with, leaving my running area surrounded by protective barriers.. Getting braver to get leaner..
VS

The map is starting to take it's own unique shape to the engine, as it seems to like a slightly fatter area around 3000 RPMs in the lower vac areas there.. Forming a little island..
I guess the engine has good/its best VE around 3k? IDK
Maybe that's a sign that my map is getting good?

A lot of good logged and analyzed pulls with effort to hit 6k.. I usually don't shift that high because their is plenty of torque in the 3s for the next gear..

On full boost it's running right inbetween the 120 and 145 kpa zones because that sensor maxes out a few psi short.. When I replace the sensor it'll throw me a bit richer when reading a touch more MAP.. Tune it some more then..

I tested the sensor with compressed air and it maxes out in the 120 kpa range.. Sometimes like 126, sometimes like 129..
Pulls have been in the mid 11s..

Changed my AFR target table a bit..

VS

I extended my cruising range up and left a bit once I noticed cruising in 5th was in the 12s or something rediculous..
100kpa feels like cruise sometimes but I know I need to keep good fuel in there..

Turning EGO on made me feel safer to run it, with pretty close to good AFRs.. EGO was just taking fuel away from me being over rich pretty much everywhere..
EGO = exhaust gas oxygen feedback in the tune, closed loop like the lambda on CIS..
Analyzing kinda hit a dead end with EGO so I started running with it off again, and analyze started giving me tighter maps like that, smoother right out of the computer..

I think I may have figured out why it starts cold so rich..
When the engine is cold, it idles higher up the map, less vacuum, so in cells I had set richer.. It seems to apply to free revving also, like holding it at 2krpm.. It's richer when it's cold..

I pretty much need my EGO to lean me out on cold starts.. I can probably set my EGO up for just the idle and cruise range now..
I haven't got PID to work for shit..

I'd probably start turning up the boost now if I had a worthy MAP sensor..
I'm feeling pretty comfortable with it and AFRs are looking really good..
Cruising with a mid 14 AFR it just drops when I step on the gas at any time..

It also hasn't exploded or leaked..
OK it might leak a little oil but if it's not dripping when I look under it idgaf.. It isn't dropping on the stick, so not consuming oil either.. 15-50 synth valvoline..

Other than the first 30-45 seconds of cold start, slightly fat idle in the mid 13s, and barely being able to notice the fuel cut overrun, it runs like you wouldn't even notice it has a crazy injection system.._________________80 Turbo - Slightly Modified

About 50mmhg = 1 psi so at 300mmhg it is adding about 6psi to the top of the WG..

I already run like 6.5 psi so adding another 6 should give me 12.5.. ish..

With the top port sealed I imagine that the pressure in it will increase as it opens, decreasing volume in the top port..

I don't know what effect this will have on boost steadyness, or the way it comes on, or creeps.. I have no idea, but I'm going to find out..

Maybe it will just give me a nice 3-5 lbs of boost increase for every 1 or 2 psi I put on the top port, due to the expected increase when it starts to open, and keep me well within the scale of the little gauge I have..

I figure I'll start with the gauge at 0 zero and see if and how much just attaching it will raise my boost.. It might..
I'll watch the gauge and see if opening the WG shows pressure up top.. I think it will..

If it seems to give me decently steady boost then maybe I will try putting a bit of pressure and see what that does..

I think adding a pressure dampner like tank inline somewhere would reduce pressure increase as the gate opens, to give the volume somewhere to go without increasing pressure as much, if it is a problem...

BTW this is the same WG diaphragm that I reinforced with black permatex coats like 4 years ago..
Holding rock steady!!

The real serious guys running 2k HP turbo drag cars use CO2 tanks to put pressure on their top ports, even with a programmable map to increase boost incrementally for launches..
https://youtu.be/LyOhfDw54zo < Haltech knows more about it than I do..

I'm not saying that this is going to be my permanent boost control solution, but something I want to experiment with..
It might be good for tuning though if it will let me hit accurate targets easily..

With the pressure regulator to the top port I always wanted to have a gauge on my top port to see what it's doing, and now I do..
And the pressure regulator.. In my experience, after it sat for a day or so, the top port would leak down, and I'd have to hit full boost like 5 times before the top port would get back up to pressure..
That was just some home made crap too though..

If I go electronic I'll probably try a 4 port..
If I go manual I'll probably be looking for an industrial style, high resolution, low pressure, pressure regulator..

I'm in the market for a beastly MAP sensor right now..
The AEM stainless ones look a whole lot like the industrial pressure transducers that I have been finding online.. Their are some transducers in the 0-50 psiA range that look tempting..

The AEM ones are like $150 for the 3-5 bar sensors..
If they are the same price do you think maybe a 3.5 or 4 bar would be better than a 5 bar? Better resolution maybe?

The industrial ones are about as much or more than the AEM ones, but are easier to find good deals on..

I read the GM ones just aren't as good as the newer ones, and if you buy an ebay 4 bar GM sensor it might be a 1 bar sensor

All of that will be a while though.. I'm about to take my intake manifold off, port it for the big TB, drill the hole bigger for my IAT, maybe add another 1/8 npt bung on it while I have it off, for a map sensor..

I might do an injector flow test while I have it apart.. See what it it will really flow through 4 injectors, with my 931 FP, at baseline, and at max enrichment..
Do the math on the weight of the sprayed fuel vs time spraying X some constants = HP_________________80 Turbo - Slightly Modified

Top one is ported, bottom is stock with the ported gasket layed over..
Yeah it's a hand made gasket, not machine perfect..
I scribed the intake through the TB while installed for my porting markings, didn't trace the rough gasket..

The biggest change is how far the small butterfly is moved over to make room for the big one..

It is also a lot more egg shaped than oval as compared to the 931 body..

The black plug is for the potentiometer TPS I'm using and the white plug gives WOT and idle switches, currently unused..

You can see the new TB also has a large vac port behind the big butterfly..

The ported vac port on the opposite side I made..
I also shortened the TB axle about an inch and raised the TPS to clear the intake runners..
I did the spring down there and drilled and pinned the axle..
I laso reground the profile of the end of the axle with a grinder in my X-Y vice and the axle in my drill press..

This TB has needle roller bearings on the axle! Cool...

The exact TB model is mentioned a few posts back..
1990 +- a few years 16 valve automatic VW..

It might not be the biggest possible TB but it is bigger and has a TPS..
It has some parts from the 931 TB and a BMW TB the way I have it..
Works good, don't like the cam on it too much..

CÚdric wrote:

How about a regular mpx 4250, couldn't it do the work?

I think that is for board mount applications right?
My microsquirt is more like a sealed unit.. It's not a DIY board like that..

My BOV is up by my TB but blows the excess back into the intake between the turbo and AFM.
So my boost blowoff could definitely be pushing my airplate up when I drop the throttle..

There is your answer to the AFR spike!

Fasteddie313 wrote:

Maybe I will try it some time with the BOV just dumping to atmosphere like normal cars and see if it spits flames instead..

Overrun cut off / VE map below idle will sort that out. No worries

Fasteddie313 wrote:

I think I may have figured out why it starts cold so rich..
When the engine is cold, it idles higher up the map, less vacuum, so in cells I had set richer.. It seems to apply to free revving also, like holding it at 2krpm.. It's richer when it's cold..

Just to be double sure, you remember that when cold the VE table is not much of use, it's more about WUE (Warm Up Enrichement) that really matters. Don't know how (if at all) you have figured out additional air for warm-up (in general you should give more fuel and more air to get engine in higher RPM for warm-up). So getting engine warmed up usually requires tuning IAV (Idle Air Valve) and WUE. THis is tricky, as you can do it only once a day

Just to be double sure, you remember that when cold the VE table is not much of use, it's more about WUE (Warm Up Enrichement) that really matters. Don't know how (if at all) you have figured out additional air for warm-up (in general you should give more fuel and more air to get engine in higher RPM for warm-up). So getting engine warmed up usually requires tuning IAV (Idle Air Valve) and WUE. THis is tricky, as you can do it only once a day

Maybe somewhere here is the answer to running rich when cold. Just a wild guess

I think I have WUE turned completely off.. I have the curve line down to the bottom atleast..

I have a ball valve bypassing my TB for my idle adjustment.. It is set to about 950 RPM when hot which gives a couple hundred RPM less at first start.. It will fire right up hitting the key..

I have a BMW E36 idle valve, that will drop in in place of my ball valve, if I want to run it, but I haven't..

Maybe jacking my cold start up to around 1300RPM for a while on cold start with the electric valve will help me..

Right now it starts in the 10s, after 20 sec I have EGO pulling it up to mid 12s, 10% authority maxes, after it warms up a bit the 10% authority is within range to bring it up to the mid 13s which is my hot idle target AFR..

It will only idle 100% smoothly up to in the 13s.. It idles like it's cammed out if I idle it in the 14s, misses a lot..
It will idle up to the 15s - 16s but misses a lot..
It idles the best in the high 12s really but I'm trying to pull it as lean as I can and maintain a smooth idle..

I think my injector flow/spray pattern at idle isn't the best.. Maybe it's the injectors, maybe the distributor, maybe because it has 8 lines to 4.. I don't know yet..

It could probably use new injectors..

Mike9311 wrote:

Keep it up! This is awesome stuff! Your engine bay reminds me of an old factory test racer

Thanks man!!
Their might not be too much new excitement for a while because I'm mostly out of accumulated parts and don't have a lot of spare cash to be dumping into more right now..
But it's not like I'm going to stop.. This car will probably be a prototype until I die, lol..

I took over my RAD fans with my MS wled and tested them a lot..
I didn't run the car to tune it to temp yet but I teted them a lot in the settings..
I was having fun, setting them to come on at %TPS, and using my throttle pedal to rev up my fans, lol.. I was entertained by that briefly..
I think I will set them to kick off with TPS just over touching the 2nd TB butterfly..

I was buying a cold thermostat and was about to buy a colder rad temp switch, thermofan switch, but then I was like HEY, I can do that for free from my MS, so I did..

The back of my head, with stock fan switch and Tstat, at idle, cycles between about 190F and 215F, which I do not like at all..
It's plenty cool while running, even hard boost, under 200 easily, but at idle, eek..
So I'm making it run colder..

....

A big part of me wants to keep my OEM coil and distributor setup but it's just too easy to do it the best way from a performance standpoint..
GM LS truck coils in a wasted spark setup.. Like this guy on a 944.. https://www.youtube.com/watch?v=7B7i-gQMGnU

I can't just fire my original coil afaik without some sort of coil driver/ignitor/excitor that I don't really understand..
I've read a bit about how to do it, by using half of a CDI box, I see some some little chinese boards that are supposed to do it, or legit ones from like AEM that aren't cheap..

Maybe I just don't understand the coil ignitor thing enough to know what junkyard part will accomplish the job?
Do you think I could find an igniter in the JY? On what and what am I looking for?
It's black magic..

The LS coils are "smart" coils so they have ignitors built right into them along with some more black magic that limits dwell themselves and stuff..

I think how 4 LS coils in wasted spark on a microsquirt works, I understand the best..
The Chevy truck coils with heatsinks are supposed to throw a MASSIVE spark, they are better from a performance standpoint than a distributor setup, and I'm pretty sure I can get myself a rack of Chevy truck coils, cut right off the main harness with all the wires, literally for a pile of old soup cans and metal scraps if I wish lol, or that old lawn mower that needs to go away.. Ya dig?
Grab whatever GM sensors and wiring connectors I want while I'm at it..
I figure if I can just get a whole pile of GM weatherpack connectors cut out of trucks, then I will have all sorts of connector parts to build what connectors I need, and just buy new pins, to do it all legit..

So it really makes sense, from a function before form standpoint, for me to run LS truck coils, so I think I will..
It will probably look kinda dumb though..

Also.. I think I will be able to run LS coils AND my OEM ignition at the same time! Just switch the sparkplug wires and swap between 2 completely separate ignition systems..
So the car will still run while I'm trying to get the LS coils setup to work.. I can build the LS ignition at my leisure that way..
And, if I do remove my distributor and coil eventually, I can easily put it back on for concourse purposes, er, for looking good..
And I won't have to ruin my distributor to lock it out to use it's VR crank/cam position sensor..

I love the distributor like a hometown highschool sweetheart, but you know that college girl working on a masters degree (LS coils) is the better logical choice..
Tough decisions..
Good thing I can cheat on the LS coils..

Thinking about how to make a decent crank sensor..

I haven't messed with the MAT sensor yet.. I stopped when I couldn't find a NPT bung to weld on in my parts piles..

I am probably posting too much babble these days but it helps me organize my thoughts.._________________80 Turbo - Slightly Modified